1. Field of the Invention
The present invention generally relates to a time division duplex (TDD) portable telephone relay device for relaying a radio telephone line between a radio base station within one radio zone in a TDD portable telephone service area including a plurality of radio zones, and a portable telephone terminal within an electrical signal insensitive region in the radio zone.
More particularly, the present invention relates to the effective use of the line by positively utilizing the TDD portable telephone relay device located in the electrical signal insensitive region.
2. Description of the Related Art
A portable telephone service area includes a plurality of radio zones. When a portable telephone terminal moves from one radio zone to another, a control signal transmit/receive means, which is called a control channel, assigns a utilizing frequency channel to the terminal. When the portable telephone terminal is not in a communicating status and a utilizing frequency channel is not still assigned to the terminal, an exclusive frequency channel predetermined in the portable telephone service area is used as the control channel. When the portable telephone terminal is in a communicating status, the control channel is maintained by means of multiplexing it with the utilizing frequency channel assigned to the terminal. The above two channels are called altogether control channels in the following description.
Currently, a portable telephone relay device is used to enable a portable telephone terminal within a certain radio zone to be used with a high line quality, even in an electrical signal insensitive region at which an electrical signal from a radio base station in the radio zone does not arrive (e.g., is not received due to the nature/characteristics of the region). For example, the electrical signal insensitive region may be found within the interior of a terminal building built in the radio zone, etc. Therefore, such a relay device allows a portable telephone to be used within a building, or other radio frequency shielding structure, in which the portable telephone would otherwise not be capable of communicating with an external base station.
FIG. 4 shows a structure of a conventional portable telephone relay device 2 in relation to a radio base station 14 and a portable telephone terminal 5.
That is, the portable telephone relay device includes a portable telephone relay device body 2 and transmit/receive antennas 3 and 4. The device is located in a building which is within a certain radio zone, but in an electrical signal insensitive region at which no electrical signal from a radio base station 14 in the radio zone is received (e.g., a terminal building 1). The transmit/receive antenna 3 is positioned outside of the terminal building 1 (e.g., on an outer wall of the terminal building 1), so as to be opposed to the radio base station 14.
Conversely, the transmit/receive antenna 4 is positioned inside of the terminal building 1, so as to be opposed to a portable telephone terminal 5 within the terminal building 1. It is noted that the number of the terminals is not limited to one although only one terminal is shown in FIG. 4.
The portable telephone relay device body 2 includes an antenna shared unit 6 connected to the transmit/receive antenna 3, an antenna shared unit 9 connected to the transmit/receive antenna 4, and a down line (e.g., down-link) amplifier 8 and an up line (e.g., an up-link) amplifier 10 which are connected to a down transmission line and an up transmission line between the antenna shared units 6 and 9, respectively.
When the portable telephone relay device is located in the terminal building 1, even if the inside of the terminal building 1 is in an electrical signal insensitive region as described above, a relay device down receive wave (e.g., signal) 21 from the radio base station 14 is received by the transmit/receive antenna 3 outside of the terminal building 1. An electrical signal corresponding to the relay device down receive wave 21 (e.g., hereinafter referred to as xe2x80x9crelay device down receive signal 21xe2x80x9d) is input to the antenna shared unit 6 and is amplified by the down line amplifier 8. The amplified signal is output to the antenna shared unit 9 and through the transmit/receive antenna 4 to the inside of the terminal building 1 as a relay device down transmit wave (e.g., signal) 22. Thus, the portable telephone terminal 5 can receive the relay device down transmit signal 22.
Additionally, a relay device up receive wave (e.g. signal) 23 output from the portable telephone terminal 5 is received by the transmit/receive antenna 4, and an electrical signal corresponding to the relay device up receive wave 23 (e.g., hereinafter referred to as xe2x80x9crelay device up receive signal 23xe2x80x9d) is input through the antenna shared unit 9 and amplified by the up line amplifier 10. Then, the amplified signal is output to the antenna shared unit 6 and through the transmit/receive antenna 3 to the radio base station 14 as a relay device up transmit signal 24.
Thus, the portable telephone relay device ensures a high line quality between the portable telephone terminal 5 and the radio base station 14, even when the portable telephone terminal 5 within the terminal building 1 is in the electrical signal insensitive region (e.g., the interior of terminal building 1 is not substantially in the electrical signal insensitive region).
However, as described above, the conventional portable telephone relay device is designed such that the electrical signal insensitive region, which is within a certain radio zone, is merely changed to a space that provides a line between the portable telephone terminal and the radio base station in the radio zone as in other general regions within the radio zone.
Further, the conventional portable telephone relay device is not designed so as to save frequency channels used in the radio zone by positively considering that the electrical wave insensitive region is a space insulated from the outside of that region with respect to the electrical wave.
Therefore, with a conventional relay device, a call which is initiated outside the building 1 must be terminated and then restarted when entering the building 1. Hence, the call cannot be continued without interruption from outside the building 1 to inside the building 1. Similarly, a call which is initiated within the building 1 cannot be continued outside the building because the frequency being used for the telephone call has not been reserved with the external base station 14.
In view of the foregoing and other problems of the conventional systems and devices, an object of the present invention is to provide a time division duplex (TDD) portable telephone relay device and a TDD portable telephone system for effectively utilizing the line and also for effectively utilizing a frequency by positively considering that a location where a portable telephone terminal exists is in an electrical wave insensitive region.
To achieve the above and other objects, according to a first aspect of the present invention, there is provided a TDD portable telephone relay device for relaying a telephone line between a radio base station within one radio zone in a TDD system portable telephone service area including a plurality of radio zones and a portable telephone terminal which is within an electrical wave insensitive region in the radio zone, the device including:
a first relay unit for relaying a radio telephone line between the radio base station and the portable telephone terminal within the electrical wave insensitive region in the radio zone of the radio base station, using a radio zone frequency channel of the radio base station; and
a second relay unit, connected to the radio base station through an exclusive wire telephone line, for conducting transmission/reception with respect to the radio base station through the exclusive wire telephone line, and for conducting transmission/reception with respect to the portable telephone terminal within the electrical wave insensitive region using a predetermined frequency channel which is not assigned to the radio zone,
wherein a relay between the radio base station and the portable telephone terminal is performed based on a control signal from the radio base station using any one of the first relay unit and the second relay unit.
According to another aspect of the present invention, there is provided a TDD portable telephone relay device for relaying a telephone line between a radio base station within one radio zone in a TDD system portable telephone service area including a plurality of radio zones and a portable telephone terminal which is within an electrical wave insensitive region in the radio zone, the device including:
a first transmit/receive antenna opposed to the radio base station out of the electrical wave insensitive region;
a second transmit/receive antenna opposed to the portable telephone terminal within the electrical wave insensitive region;
a first distributor including first and second output terminals, and for distributing a relay device down receive signal transmitted from the first transmit/receive antenna to output the receive signal from said first and second output terminals;
a synchronous receive section, connected to the first output terminal of the first distributor, for demodulating the relay device down receive signal as inputted to obtain a synchronous signal;
a second distributor including first, second and third output terminals, and for distributing a relay device up receive signal transmitted from the second transmit/receive antenna to output the receive signal from said first, second and third output terminals;
a position detecting unit, connected to the first output terminal of the second distributor, for detecting a frequency channel used by the portable telephone terminal positioned within the electrical wave insensitive region, to output a detection result to the radio base station through an exclusive wire telephone line;
a predetermined-size base station section, connected to the exclusive wire telephone line, for being controlled upon reception of the control signal transmitted from the radio base station through the exclusive wire telephone line, and for outputting a modulated wave electric signal obtained by modulating speech data transmitted from the radio base station through the exclusive wire telephone line using a predetermined frequency channel other than a radio zone frequency channel of the radio base station,
the predetermined-size base station section further for receiving the relay device up receive signal outputted from the second output terminal, outputting only the receive signal for which the predetermined frequency channel is used among the relay device up receive signals to the radio base station through the exclusive wire telephone line, and outputting information relating to the use state of the predetermined frequency channel to the radio base station through the exclusive wire telephone line;
a synthesizer, connected to a modulated wave electric signal output terminal of the predetermined-size base station section and the second output terminal of the first distributor, for synthesizing and outputting respective outputs from said modulated wave electrical signal output terminal and said second output terminal of said first distributor;
a first circulator, connected to the first transmit/receive antenna, an input side of the first distributor, and the third output terminal of the second distributor, for outputting the receive signal from the first transmit/receive antenna to the input side of the first distributor, and outputting the output signal from the third output terminal of the second distributor to the second transmit/receive antenna; and
a second circulator, connected to an output side of the synthesizer, an input terminal of the second distributor, and the second transmit/receive antenna, for outputting the output signal of the synthesizer to the second transmit/receive antenna and outputting the receive signal from the second transmit/receive antenna to an input terminal of the second distributor.
According to another aspect of the present invention, there is provided a TDD portable telephone system, including:
a radio base station disposed within one radio zone in a TDD portable telephone service area including a plurality of radio zones;
a portable telephone terminal disposed within an electrical wave insensitive region of the radio zone;
a TDD portable telephone relay device; and
an exclusive wire telephone line connecting the TDD portable telephone relay device and the radio base station.
According to another aspect of the present invention, there is provided a TDD portable telephone system, including:
a radio base station disposed within one radio zone in a TDD portable telephone service area including a plurality of radio zones;
a portable telephone terminal disposed within an electrical wave insensitive region of the radio zone;
a TDD portable telephone relay device; and
an exclusive wire telephone line connecting the TDD portable telephone relay device and the radio base station,
wherein, when an unused channel exists in a predetermined frequency channels according to a information relating to a use state of a predetermined frequency channel transmitted from a predetermined-size base station section of the TDD portable telephone relay device, for conducting transmission/reception to the portable telephone terminal through a second relay unit using an unused frequency channel, the radio base station transmits a control signal to the portable telephone terminal using a control channel to fix a channel used by the portable telephone terminal to the unused channel.
According to another aspect of the present invention, there is provided a TDD portable telephone system, including:
a radio base station disposed within one radio zone in a TDD portable telephone service area including a plurality of radio zones;
a portable telephone terminal disposed within an electrical wave insensitive region of the radio zone;
a TDD portable telephone relay device; and
an exclusive wire telephone line connecting the TDD portable telephone relay device and the radio base station,
wherein, when it is judged based on a detection signal of a position detecting unit that the portable telephone terminal is outside the electrical wave insensitive region when the transmission/reception between the portable telephone terminal and the TDD portable telephone relay unit is conducted, using a predetermined frequency channel within frequency channels which are not assigned to the radio zone, the radio base station transmits a control signal to the portable telephone terminal using the control channel to change a use channel from the predetermined frequency channel to a radio zone frequency channel of the radio base station, and controls a second relay unit to finish the transmission/reception to the portable telephone terminal.
With the TDD portable telephone relay device and TDD portable telephone system of the present invention, the line and the frequency can be utilized effectively.
Further, unlike the conventional portable telephone relay device, the portable telephone relay device of the present invention is affirmatively designed such that even when the portable telephone is in the electrical signal insensitive region, which is within a certain radio zone, the relay device provides a line between the portable telephone terminal and the radio base station in the radio zone as in other general regions within the radio zone.
Moreover, the inventive portable telephone relay device is designed to efficiently use (and save) frequency channels in the radio zone by considering characteristics of the electrical wave insensitive region.